<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
</head>
<body>
    <h1>这里是标题</h1>
    <div>这里是内容，图片等等</div>
    <h5>这里是副标题</h5>
    <script>
        let a = 0;
        for (let i = 0; i < 5 ; i++) {
            a++;
            if( i == 4){
                console.log(a);
                break;
            }    
        }
    </script>
</body>
</html>

